<!-- 从fn的tld中,可以清楚的看到具体的方法声明(function-signature)及示例(example),方法声明处可以看到参数类型及返回值类型。看懂这个tld就可以自己写自定义标签了 -->
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://www.360doc.com/" xmlns:xsi="http://www.360doc.com/" xsi:schemaLocation="http://www.360doc.com/ http://www.360doc.com/" version="2.0"> <description>JSTL 1.1 functions library</description> <display-name>JSTL functions</display-name> <tlib-version>1.1</tlib-version> <short-name>fn</short-name> <uri>http://java./jsp/jstl/functions</uri>
<function> <description> Tests if an input string contains the specified substring. </description> <name>contains</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>boolean contains(java.lang.String, java.lang.String)</function-signature> <example> <c:if test="${fn:contains(name, searchString)}"> </example> </function>
<function> <description> Tests if an input string contains the specified substring in a case insensitive way. </description> <name>containsIgnoreCase</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>boolean containsIgnoreCase(java.lang.String, java.lang.String)</function-signature> <example> <c:if test="${fn:containsIgnoreCase(name, searchString)}"> </example> </function>
<function> <description> Tests if an input string ends with the specified suffix. </description> <name>endsWith</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>boolean endsWith(java.lang.String, java.lang.String)</function-signature> <example> <c:if test="${fn:endsWith(filename, ".txt")}"> </example> </function>
<function> <description> Escapes characters that could be interpreted as XML markup. </description> <name>escapeXml</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String escapeXml(java.lang.String)</function-signature> <example> ${fn:escapeXml(param:info)} </example> </function>
<function> <description> Returns the index withing a string of the first occurrence of a specified substring. </description> <name>indexOf</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>int indexOf(java.lang.String, java.lang.String)</function-signature> <example> ${fn:indexOf(name, "-")} </example> </function>
<function> <description> Joins all elements of an array into a string. </description> <name>join</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String join(java.lang.String[], java.lang.String)</function-signature> <example> ${fn:join(array, ";")} </example> </function>
<function> <description> Returns the number of items in a collection, or the number of characters in a string. </description> <name>length</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>int length(java.lang.Object)</function-signature> <example> You have ${fn:length(shoppingCart.products)} in your shopping cart. </example> </function>
<function> <description> Returns a string resulting from replacing in an input string all occurrences of a "before" string into an "after" substring. </description> <name>replace</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String replace(java.lang.String, java.lang.String, java.lang.String)</function-signature> <example> ${fn:replace(text, "-", "•")} </example> </function>
<function> <description> Splits a string into an array of substrings. </description> <name>split</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String[] split(java.lang.String, java.lang.String)</function-signature> <example> ${fn:split(customerNames, ";")} </example> </function>
<function> <description> Tests if an input string starts with the specified prefix. </description> <name>startsWith</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>boolean startsWith(java.lang.String, java.lang.String)</function-signature> <example> <c:if test="${fn:startsWith(product.id, "100-")}"> </example> </function>
<function> <description> Returns a subset of a string. </description> <name>substring</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String substring(java.lang.String, int, int)</function-signature> <example> P.O. Box: ${fn:substring(zip, 6, -1)} </example> </function>
<function> <description> Returns a subset of a string following a specific substring. </description> <name>substringAfter</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String substringAfter(java.lang.String, java.lang.String)</function-signature> <example> P.O. Box: ${fn:substringAfter(zip, "-")} </example> </function>
<function> <description> Returns a subset of a string before a specific substring. </description> <name>substringBefore</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String substringBefore(java.lang.String, java.lang.String)</function-signature> <example> Zip (without P.O. Box): ${fn:substringBefore(zip, "-")} </example> </function>
<function> <description> Converts all of the characters of a string to lower case. </description> <name>toLowerCase</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String toLowerCase(java.lang.String)</function-signature> <example> Product name: ${fn:toLowerCase(product.name)} </example> </function>
<function> <description> Converts all of the characters of a string to upper case. </description> <name>toUpperCase</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String toUpperCase(java.lang.String)</function-signature> <example> Product name: ${fn:UpperCase(product.name)} </example> </function>
<function> <description> Removes white spaces from both ends of a string. </description> <name>trim</name> <function-class>org.apache.taglibs.standard.functions.Functions</function-class> <function-signature>java.lang.String trim(java.lang.String)</function-signature> <example> Name: ${fn:trim(name)} </example> </function>
</taglib>
<!-- 函数说明 -->
函数名 |
函数说明 |
使用举例 |
fn:contains |
判断字符串是否包含另外一个字符串 |
<c:if test="${fn:contains(name, searchString)}"> |
fn:containsIgnoreCase |
判断字符串是否包含另外一个字符串(大小写无关) |
<c:if test="${fn:containsIgnoreCase(name, searchString)}"> |
fn:endsWith |
判断字符串是否以另外字符串结束 |
<c:if test="${fn:endsWith(filename, ".txt")}"> |
fn:escapeXml |
把一些字符转成XML表示,例如<字符应该转为< |
${fn:escapeXml(param:info)} |
fn:indexOf |
子字符串在母字符串中出现的位置 |
${fn:indexOf(name, "-")} |
fn:join |
将数组中的数据联合成一个新字符串,并使用指定字符格开 |
${fn:join(array, ";")} |
fn:length |
获取字符串的长度,或者数组的大小 |
${fn:length(shoppingCart.products)} |
fn:replace |
替换字符串中指定的字符 |
${fn:replace(text, "-", "•")} |
fn:split |
把字符串按照指定字符切分 |
${fn:split(customerNames, ";")} |
fn:startsWith |
判断字符串是否以某个子串开始 |
<c:if test="${fn:startsWith(product.id, "100-")}"> |
fn:substring |
获取子串 |
${fn:substring(zip, 6, -1)} |
fn:substringAfter |
获取从某个字符所在位置开始的子串 |
${fn:substringAfter(zip, "-")} |
fn:substringBefore |
获取从开始到某个字符所在位置的子串 |
${fn:substringBefore(zip, "-")} |
fn:toLowerCase |
转为小写 |
${fn.toLowerCase(product.name)} |
fn:toUpperCase |
转为大写字符 |
${fn.UpperCase(product.name)} |
fn:trim |
去除字符串前后的空格 |
${fn.trim(name)} |
<!-- 函数说明 -->
函数 |
描述 |
fn:contains(string, substring) |
如果参数string中包含参数substring,返回true |
fn:containsIgnoreCase(string, substring) |
如果参数string中包含参数substring(忽略大小写),返回true |
fn:endsWith(string, suffix) |
如果参数 string 以参数suffix结尾,返回true |
fn:escapeXml(string) |
将有特殊意义的XML (和HTML)转换为对应的XML character entity code,并返回 |
fn:indexOf(string, substring) |
返回参数substring在参数string中第一次出现的位置 |
fn:join(array, separator) |
将一个给定的数组array用给定的间隔符separator串在一起,组成一个新的字符串并返回。 |
fn:length(item) |
返回参数item中包含元素的数量。参数Item类型是数组、collection或者String。如果是String类型,返回值是String中的字符数。 |
fn:replace(string, before, after) |
返回一个String对象。用参数after字符串替换参数string中所有出现参数before字符串的地方,并返回替换后的结果 |
fn:split(string, separator) |
返回一个数组,以参数separator 为分割符分割参数string,分割后的每一部分就是数组的一个元素 |
fn:startsWith(string, prefix) |
如果参数string以参数prefix开头,返回true |
fn:substring(string, begin, end) |
返回参数string部分字符串, 从参数begin开始到参数end位置,包括end位置的字符 |
fn:substringAfter(string, substring) |
返回参数substring在参数string中后面的那一部分字符串 |
fn:substringBefore(string, substring) |
返回参数substring在参数string中前面的那一部分字符串 |
fn:toLowerCase(string) |
将参数string所有的字符变为小写,并将其返回 |
fn:toUpperCase(string) |
将参数string所有的字符变为大写,并将其返回 |
fn:trim(string) |
去除参数string 首尾的空格,并将其返回 |
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